Rather than executing a new if() statement for each mode, you might want to check out elsif() instead. This has the advantage that your script will exit quicker as it will not check every single if() statement to see if it is true or not. It will skip to the end of the if/elsif blocks once it has been satisfied in one of the conditionals. Your example would change to the following: 

my $mode = param('mode');

# Main
if (not defined $mode) {
 # ...
}

# After upload
elsif ($mode eq 'secondstage') {
 # ...
}

# Final stage
elsif ($mode eq 'finalstage') {
 # ...
}

[download]

To create cleaner code, I tend to do something like this: 


sub main {
 # Main page
}

sub secondstage {
 # After upload
}

sub finalstage {
 # final stage
}

sub _invalid {
 # Output error message: no such mode
}

my $modes = {
 ''          => \&main,
 secondstage => \&secondstage,
 finalstage  => \&finalstage,
 _invalid    => \&invalid
};

my $mode = param('mode');
$modes->{ exists $modes->{$mode} ? $mode : '_invalid' }->();

[download]

If the above content is missing any vital points or you feel that any of the information is misleading, incorrect or irrelevant, please feel free to downvote the post. At the same time, reply to this node or /msg me to tell me what is wrong with the post, so that I may update the node to the best of my ability. If you do not inform me as to why the post deserved a downvote, your vote does not have any significance and will be disregarded.

In reply to Re^2: interactive CGI script? by Coruscate
in thread interactive CGI script? by vinforget

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